Linear actuator assembly

ABSTRACT

A linear actuator assembly ( 30 ) having an inner sleeve ( 100 ) which moves in a first direction or in an opposite second direction relative to a fixed outer sleeve ( 90 ) between a fully extended position and a fully retracted position. The linear actuator assembly ( 30 ) includes a stop mechanism ( 99, 112 ) limiting the movement of the inner sleeve ( 100 ) relative to the outer sleeve ( 90 ) in the extended position, the stop mechanism ( 99, 112 ) having a first portion ( 99 ) associated with said outer sleeve ( 90 ) and a second portion ( 112 ) associated with said inner sleeve ( 100 ) with the first ( 99 ) and second ( 112 ) portions abutting each other when said inner sleeve ( 100 ) is in the extended position to define a hard stop.

CROSS REFERENCE TO RELATED APPLICATION

This application is the National Stage of International PatentApplication No. PCT/IB2012/002431, filed on Nov. 21, 2012, which claimsthe benefit of U.S. Provisional Patent Application Ser. No. 61/562,149filed Nov. 21, 2011, the contents of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a linear actuator assembly,and more specifically to a linear actuator assembly for use in shift bywire transmission systems.

2. Description of the Related Art

A technology that is becoming increasingly common in gearboxes invehicles is so-called “shift by wire” technology. In other words asystem where there is no mechanical connection between the gear leverand the gearbox. Instead, such systems have an electronic connectionbetween a gear selector, arranged in association with the gear lever,and the gearbox. The position of the gear lever in the gear selector isread off by a sensor arrangement that sends information about theposition of the gear lever to the gearbox, whereupon a required gearposition is assumed.

Linear electromechanical actuators, also known as linear actuatorassemblies, are useful in vehicle transmissions to facilitate gearselection and provide shift-by-wire functionality. These linear actuatorassemblies offers a number of advantages over electromechanical systemsbased on electric motors and gearboxes in that their outer appearance issimilar to a mechanical cable end and thus allows simple attachment andinterface to existing Bowden cable operated transmissions. The presentinvention provides simple, robust linear actuator assemblies havingelectronic and mechanical control.

SUMMARY OF THE INVENTION AND ADVANTAGES

The present invention provides a linear actuator assembly comprising ahousing and a motor at least partially supported by the housing. Thelinear actuator assembly also comprises an outer sleeve coupled to thehousing and defining a working chamber with the outer sleeve defining alongitudinal axis and an inner sleeve disposed within the workingchamber and movable between a retracted position and an extendedposition along the longitudinal axis relative to the outer sleeve. Theinner sleeve has a first end and an opposing second end and a series ofthreads disposed along at least a portion of the sleeve. A screw iscoupled to the motor and extends outwardly from the motor along thelongitudinal axis with the screw having a threaded exterior surfaceengaging the threads of the inner sleeve, wherein the rotation of themotor rotates the screw through the threads of the inner sleeve andfacilitates the movement of the inner sleeve between the retracted andextended positions along the longitudinal axis. The linear actuatorassembly also comprises a stop mechanism limiting the movement of theinner sleeve relative to the outer sleeve in the extended position, thestop mechanism having a first portion associated with the outer sleeveand a second portion associated with the inner sleeve with the first andsecond portions abutting each other when the inner sleeve is in theextended position to define a hard stop.

The linear actuator assembly may be utilized in transmission shift bywire assemblies of vehicles.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a linear actuator assembly in accordancewith one embodiment of the present invention.

FIG. 2A is an exploded perspective view of the linear actuator assemblyof FIG. 1.

FIG. 2B is a rear perspective view a portion of a housing and an outersleeve of the linear actuator assembly of FIG. 2A.

FIG. 2C is a front perspective view of FIG. 2B.

FIG. 2D is another rear perspective view of the portion of the housingand outer sleeve with an inner sleeve and screw disposed within theouter sleeve of the linear actuator assembly of FIG. 2A.

FIG. 3 is a partially cross-sectioned side view the linear actuatorassembly of FIG. 1.

FIG. 4 is a partially cross-sectioned top view of the linear actuatorassembly connected to a gearshift lever in a fully retracted position.

FIG. 5 is a partially cross-sectioned top view of the linear actuatorassembly connected to a gearshift lever in a fully extended position.

FIG. 6 is a partially cross-sectioned side view of a portion of thelinear actuator assembly of FIG. 1.

FIG. 7 is a perspective view of the linear actuator assembly mountedwithin an alternative bracket assembly in accordance with anotherembodiment of the present invention.

FIG. 8 is a partially cross-sectioned side of a linear actuator assemblyconnected to a gearshift lever in a fully retracted position inaccordance with yet another embodiment of the present invention.

FIG. 9 is a partially cross-sectioned side of a linear actuator assemblyconnected to a gearshift lever in a fully extended position inaccordance with the embodiment of FIG. 8.

FIG. 10 is a partially cross-sectioned side of a linear actuatorassembly connected to a gearshift lever illustrating the positioning ofa gearshift lever coupled to the linear actuator assembly in threepositions in accordance with the embodiment of FIG. 8.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the FIGS. 1-6, wherein like numerals indicate like orcorresponding parts throughout several views, a linear actuator assembly30 in accordance with one exemplary embodiment is generally shown. Thelinear actuator assembly 30 may be utilized in transmission shift bywire assemblies of vehicles.

The linear actuator assembly 30 includes a motor 32 disposed in and atleast partially supported by a housing 34. The housing 34, in certainembodiments, includes a first portion 35 mated or otherwise fixedlycoupled to a second portion 37. The motor 32 includes an output shaft 36extending through an aperture 38 in a ring gear 56 that is fixedlycoupled to the motor 32. The assembly 30 may be seated onto, or fixedlyattached, to a bracket assembly 31.

The output shaft 36 includes a first end extending into the motor 32 andsecond end 44 extending outwardly away from the motor 32. The second end44 preferably includes a splined outer surface 46. The motor 32 andoutput shaft 36 are shown schematically in FIG. 3-5.

The assembly 30 also includes a gear assembly 50 including a pluralityof planetary gears 52 located radially around and engaged with acentral, or sun gear 54. The planetary gears 52 are located radiallywithin the ring gear 56 that is fixed within the space between thehousing 34 and the motor 32. The sun gear 54 preferably includes aninternal aperture that mates to the outer surface 46 of the output shaft36 when the output shaft 36 is coupled to the sun gear 54. in certainembodiments, the output shaft 36 is press fit within the aperture of thesun gear 54. When powered, the output shaft 34 of the motor 32 willrotate the sun gear 54, which in turn rotates the plurality of planetarygears 52 in response. As the planetary gears rotate 52, they travel in acircular manner along the geared inner surface of the fixed ring gear 56and about a center axis 62. As best shown in FIG. 2A, each of theplanetary gears 52 is rotatably mounted to a planet carrier 64 using apin or other fastening device. The planet carrier 64 includes anaperture 74.

The linear actuator assembly 30 has an outer sleeve 90 defining a firstend 92 and a second end 94. The outer sleeve 90 also defines alongitudinal axis and an interior surface 96 defining a working chamberand an exterior surface 97. As best shown in FIG. 2B, the interiorsurface 96 also includes a series of inwardly projecting flanges 93,wherein a respective pair of the series of flanges 93 defines arespective guide slot 95. The longitudinal axis may be parallel to orequivalent to the center axis 62. The working chamber extends from thefirst end 92 to the second end 94. A cap or seal-like structure 98having a shoulder 99 is mounted to the second end 94 of the outer sleeve90. In the illustrated embodiment, the outer sleeve 90 is a portion ofthe housing 34 (i.e., is integrally formed with the housing 34). Inparticular, the outer sleeve 90 abuts the second portion 37 of thehousing 34 to define a stepped portion 41. Alternatively, the sleeve 90may be separately affixed or otherwise coupled to and extend from thehousing 34.

The linear actuator assembly 30 also has an inner sleeve 100. As bestshown in FIGS. 2D and 3-5, the inner sleeve 100 is disposed within theworking chamber of the outer sleeve 90. The inner sleeve 100 has a firstend 102 and a second end 104. The inner sleeve 100 also defines thelongitudinal axis and an interior surface 106 defining an inner region108. Referring specifically to FIGS. 2C, 2D and 4-5, the inner sleeve100 further includes an exterior surface 110 having a plurality of tabs111, with each of the plurality of tabs 111 disposed within a respectiveone of the plurality of guide slots 95 of the outer sleeve 90, as bestshown in FIG. 2D. Also, each of the tabs 111 define a respectiveshoulder 112 near the first end 102. In addition, the inner sleeve 100is cylindrical near the second end 104, but becomes semi-cylindricalnearer to the first end 102, and therefore defines a cylindrical region103 and a semi-cylindrical region 105. A slot 109 is formed in theinterior surface 106 of the semi-cylindrical region 105 of the innersleeve 100. Further, the tabs 111 extend beyond the semi-cylindricalregion 105 at the first end 102 of the inner sleeve 100 towards themotor 32. As best shown in FIG. 6, the portions of the tabs 111 thatextend beyond the semi-cylindrical region 105 of the first end 102define a gap 114 in the inner sleeve 100 wherein a portion of the screw102 remains exposed.

A protective shield 107 is mounted to or otherwise coupled to the secondend 104 of the inner sleeve 100 and extends from the second end 104 overthe exterior surface 97 of the outer sleeve 90. The shield 107 can beintegrally formed with the inner sleeve 100 or, as shown, may be formedas a separate piece and coupled to the inner sleeve 100 at the secondend 104. The shield 107 preferably surrounds the inner sleeve 100 suchthat the inner sleeve 100 is not exposed during movement and such thatthe shield 107 overlies at least a portion of the outer sleeve 90 duringmovement between a fully extended position, as shown in FIG. 5, and afully retracted position, as shown in FIG. 4. An o-ring (not shown)mounted on a groove within the inner surface of the shield 107 andabutting the outer sleeve 90 may be utilized to seal the shield 107 tothe outer sleeve 90.

The linear actuator assembly 30 further includes a screw 120. The screw120 is disposed in the inner region 108 of the inner sleeve 100. Thescrew 120 has a first end 122 and a second end 124. The screw 120 alsohas a threaded exterior surface 126 along a portion of its length. Anadaptor 130 coupled within the housing 34 is fixedly coupled to thefirst end 122 of the screw 120. The outer surface 134 of the adaptor 130is preferably press fit or otherwise contained within the aperture 74 ofthe planet carrier 64. As such, the screw 120 is coupled to the motor 32through the gear assembly 50 (i.e., the gear assembly 50 is disposedbetween the motor 32 and the screw 120) and extends outwardly from themotor 32 along the longitudinal axis. The assembly 30 also includes abearing 80 coupled within the housing 34 with the adaptor 130 beingsupported by the bearing 80 to facilitate rotation of the adaptor 130,fix the screw 120 longitudinally, and absorb axial forces to protect themotor 32.

The inner sleeve 100 includes a nut 140 having a threaded interiorsurface 142 defining a series of threads which are threadingly engagedwith the threaded exterior surface 126 of the screw 120 and is affixedwithin the slot 109 of the interior surface 106 of the inner sleeve 100.Thus, the nut 140 remains in a fixed location relative to the innersleeve 100 as the screw 120 is rotated such that the nut 140 and theinner sleeve 100 move as a unit. In alternative embodiments, a nut 140is not utilized, and thus the threaded exterior surface 126 of the screw120 is threadingly engaged with the threaded interior surface 142 of theinner sleeve 140 along the portion of the length illustrated asincluding the nut in FIGS. 1-7.

When powered, the output shaft 36 of the motor 32 will rotate the sungear 54, which in turn rotates the plurality of planetary gears 52 andplanet carrier 64 around the center axis 62. The rotation of the planetcarrier 64 in turn rotates the adaptor 130, which in turn rotates thescrew 120, which will rotate within the threaded interior surface 142 ofthe nut 140. The nut 140 and inner sleeve 100 will move axially as aunit along the length of the screw 120 and outer sleeve 90, with therespective plurality of tabs 111 moving axially within each of therespective plurality of guide slots 95 of the outer sleeve 90 and alongthe longitudinal axis in response to the rotation of the screw 120.Notably, the coupling of the plurality of tabs 111 within the respectiveplurality of guide slots 95 prevents the inner sleeve 100 from rotatingas a unit with the screw 120. The screw 120 remains longitudinally fixedrelative to the outer sleeve 90 and the longitudinal axis whilerotating. In addition, the outer sleeve 90 remains fixed to the housing34 and fixed relative to the housing 34 during movement of the innersleeve 100.

The inner sleeve 100 can be linearly displaced axially along thelongitudinal axis relative to the screw 120 and outer sleeve 90 in afirst longitudinal direction when the motor 32 is rotating in a firstdirection (i.e., the first rotational direction) until such time as theshoulder 112 of the tab 111 on the inner sleeve 100 is brought intocontact with the shoulder 99 of the cap 98 on the outer sleeve 90.Stated differently, the linear actuator assembly includes a stopmechanism that limits the movement of the inner sleeve 100 relative tothe outer sleeve 90 at the fully extended position, as shown in FIG. 5,when a first portion associated with the outer sleeve 90 and a secondportion associated with the inner sleeve 100 abut each other to define ahard stop. As the inner sleeve 100 is displaced, the shield 107 is alsolinearly displaced axially in a direction away from the stepped portion41 of the housing 34. Rotating the output shaft 36 and the motor 32 inthe opposite direction (i.e., the second rotational direction) willallow the inner sleeve 100 to move axially in the opposite lineardirection along the longitudinal axis (i.e. a second longitudinaldirection) toward the stepped portion 41 of the housing 34. Thismovement will continue until the tabs 111 contact the adaptor 30, orwherein the protective shield 107 contacts the stepped portion 41 of thehousing 34, or both, as described in greater detail below in the fullyretracted position, as shown in FIG. 4. Thus, the length of displacementof the inner sleeve 100 relative to the outer sleeve 90 and screw 120 islimited.

The linear actuator assembly 30 also includes a shaft 170 with the shaft170 having an axis. The shaft 170 also has an exterior surface 172 and afirst end 174. The linear actuator assembly 30 also has a gear 176supported within the housing 34 with the gear 176 having an exteriorsurface 178. The shaft 170 is disposed in and abuts the gear 176.Alternatively, the shaft 170 and gear 176 may be integrally formed as asingle piece or mounted together for concurrent rotation. The exteriorsurface 178 of the gear 176 has teeth. The gear 176 also has an emitter,shown in FIGS. 1-6 as a magnet 180, which is attached to and abuts thefirst or distal end 174 of the shaft 170. The magnet 180 is located inclose proximity to a sensor, shown in FIG. 2 as a Hall Effect sensor184. The magnet 180 has a North Pole 182 and a South Pole 183 that emitsa magnetic field. In alternative arrangements, the magnet 180 may beattached to any other portion of the gear 176 or shaft 170. Further, itcan be appreciated that other sensor arrangements could be implemented.A printed circuit board 185 electrically coupled to the Hall Effectsensor 184 is disposed within the housing 34. The printed circuit board185 is electrically coupled to a controller 101.

The teeth of the gear 176 are disposed in are threadingly engaged withthe threaded exterior surface 126 of the screw 120 such that the gear176 rotates the shaft 170 and the magnet 180 during the movement of theinner sleeve 100. As the magnet 180 rotates, the circular movement ofthe North Pole 182 and the South Pole 183 create a change in themagnetic field. The Hall Effect sensor 184 that is positioned adjacentthe magnet 180 detects the change in the magnetic field. The differentmagnetic field measurements detected by the Hall Effect sensor 184 areelectronically transmitted to the printed circuit board 185 and thecontroller 101 to determine the axial position of the inner sleeve 100relative to the outer sleeve 90 along the longitudinal axis. The gear176 should have a gear ratio with the screw 120 that would rotate themagnet 180 approximately 300 degrees for the entire linear displacementof the inner sleeve 100. The large amount of rotation will provide goodvariation in the magnetic field between the different positions of theinner sleeve 100 that allows for an accurate determination of the linearpositioning of the inner sleeve 100 relative to the outer sleeve 90 inthe assembly 30.

As mentioned above, the gear 176 also includes a notch, or cut-outregion 177, that removes approximately 60-120 degrees of the teeth ofthe gear 176 and therefore defines a first end 179 and a second end 181of the teeth of the gear 176. In the fully retracted position, as shownin FIG. 4, the first end 102 of the inner sleeve 100 is positionedwithin the notch 177 of the gear 176 and the second end 181 of the gear176 is in contact with the threaded portion of the exterior surface 126of the screw 120. The gap 114 formed in the inner sleeve 100 providesthe necessary clearance for the second end 181 of the gear 176 to remainin contact with the screw 120. In this position, the inner sleeve 100 isprevented from retracting further towards the motor 32 due the contactof the tabs 111 with the adaptor 30 or wherein the protective shield 107contracts the stepped portion 41 of the housing 34. In the fullyextended position, as shown in FIG. 5, the gear 176 has rotatedclockwise approximately 250-300 degrees relative to the positioning ofthe gear 176 when in the fully retracted position. Stated differently,the complete rotation of the gear 175 from the fully retracted position,as shown in FIG. 4, to the fully extended position, as shown in FIG. 5,is approximately 250-300 degrees.

In certain embodiments, as noted above, the linear actuator assembly 30is utilized in transmission shift by wire assemblies of vehicles. Inthese embodiments, as shown best in FIGS. 3-5, a first terminal 186,having a terminal end fitting 188, is coupled to a gear shift lever 224.The terminal end fitting 188 extends into the inner region 108 of theinner sleeve 100 and is connected or otherwise mounted to the innersleeve 100.

The first terminal 186 includes an interior region 200 that is designedto be mounted about a pin 220 of the gear shifter 224. The configurationof the interior region 200 of the first terminal 186 and the gearshifter 224 can be of any suitable design. Once mounted, the pin 220 mayarticulate within the interior region 200 to shift the transmission of avehicle as desired. The first terminal 186 moves as a unit with theinner sleeve 100 from a first position, corresponding to the fullyretracted position of the linear actuator assembly 30, to a secondposition corresponding to the fully extended position of the linearactuator assembly 30. The gear shifter 224 is displaced as the innersleeve 100 of the linear actuator assembly 30 moves from the fullyretracted position to the fully extended position, as best shown inFIGS. 4 and 5.

Also shown in FIGS. 1-6 is a second terminal 235 which is coupled tofirst portion 35 of the housing 34 near the motor 32. The secondterminal 235 is structurally similar to the first terminal 186, and mayaccommodate a pin 240 within an interior region 245 similar to the firstterminal 186. However, as opposed to the first terminal 186, the seconddamper assembly 235 is not displaced axially relative to the housing 34and motor 32 as the linear actuator assembly 30 is moved from a fullyretracted position to a fully extended position. Stated differently, thesecond terminal 235, as one of ordinary skill readily recognizes, is afixed terminal in a transmission shift by wire assembly, whereas thefirst terminal 186 is considered the displaceable terminal. However,during gear shifting, the linear actuator assembly 30 may articulate onthe pin 240 to facilitate the up or down displacement of the gearshifter 224 during the gear shifter's pivotal movement.

Referring to FIG. 7, an alternative mounting bracket assembly 310 to thebracket assembly 31 for attachment to the linear actuator assembly 30 isgenerally shown. The mounting bracket assembly 310 includes a mount 312.The mount 312 includes a plate 314 having a first arm 316 and a secondarm 318. In the embodiment shown, the first arm 316 and second arm 318are generally L-shaped and have an interior surface. The interiorsurfaces are perpendicular to the plate 314 and parallel to each other.

The mounting bracket assembly 310 also includes an actuator bracket 326rotationally mounted to the first arm 316 and the second arm 318 about afirst pivot axis with the first pivot axis being transverse to thelongitudinal axis. The housing 34 is supported by the actuator bracket326 to permit the housing 34 to rotate about the first pivot axis,relative to the plate 314, as shown by arrow 322, to assist withinstallation of the linear actuator assembly 30 on the first terminal186 and on the gear shifter 224.

The actuator bracket 326 has a bearing 346 defining a second pivot axistransverse to the longitudinal axis and the first pivot axis. Thehousing 34 has a journal 348, 350 rotatably mounted about the bearing346 to permit the housing 34 to rotate about the second pivot axis.Rotation about the second pivot axis will typically occur duringoperation of the linear actuator assembly 30.

The bearing 346 of the actuator bracket 326 includes a first end 330 anda second end 332. The first end 330 includes a curved surface 334 andthe second end 332 includes another curved surface 336. The first end330 and second end 332 also include angled surfaces 338, 340, 342, 344.

The journal 348, 350 of the housing 34 is further defined as two curvedribs 348, 350. The linear actuator assembly 30 can rotate about thesecond pivot axis of the bearing 346 by the curved ribs 348, 350 alongthe curved surfaces 334, 336, as shown by arrow 320. The rotation aboutthe second pivot axis is limited when the curved ribs 348, 350 of thejournal 348, 350 abut the angled surfaces 338, 340, 342, 344 of thebearing 346. As mentioned above, rotation of the linear actuatorassembly 30 is necessary to accommodate the arcuate motion of the gearshifter 224 (see FIG. 4).

Referring to the FIGS. 8-10, wherein like numerals indicate like orcorresponding parts throughout several views, a linear actuator assembly400 in accordance with another exemplary embodiment is shown. Similar tothe linear actuator assembly 30, the linear actuator assembly 400 may beutilized in transmission shift by wire assemblies of vehicles.

The linear actuator assembly 400 includes a motor 412 coupled within ahousing 413. The motor 412 includes an output shaft 414.

The output shaft 414 includes a first end 416 and second end 418. Themotor 412 is disposed around and abuts the first end 416 of the outputshaft 414. The second end 418 is disposed in and abuts a bearing 420.The bearing 420 protects the motor 412 from axial forces. The motor alsoabuts a case 422. The case 422 is disposed around the bearing 420 andincludes a printed circuit board 424 and Hall Effect sensor 426. Theprinted circuit board 424 is electrically coupled to a controller 101,which typically includes a central processing unit.

The linear actuator assembly 400 has an outer sleeve 428 defining afirst end 430 and a second end 432. The first end 430 is disposed in thecase 422 and abuts the bearing 420. The outer sleeve 428 also has anaxis and an interior surface 434 defining a working chamber. The workingchamber extends from the first end 430 to the second end 432. The outersleeve 428 further includes an aperture 436 and a pin 438 with the pin438 disposed in the aperture 436 and positioned near the second end 432.The outer sleeve 428 further defines a second aperture 437, or removedsection, located at the second end 432.

The linear actuator assembly 400 also has an inner sleeve 440. The innersleeve 440 is disposed within the working chamber of the outer sleeve428. The inner sleeve 440 has a first end 442 and a second end 444. Theinner sleeve 440 also has an axis and an interior surface 446 defining asecond chamber. The second chamber extends from the first end 442 to thesecond end 444. The interior surface 446 of the second chamber includesinwardly projecting collar 443 having a threaded surface 445 defining aseries of threads. The collar 443 projects inwardly into the secondchamber and is preferably near the first end 442. The collar 443 may beintegrally formed with the inner sleeve 440, as shown, or separatelycoupled to the inner sleeve 440. Referring specifically to FIG. 8, theinner sleeve 440 further includes an exterior surface 448 and a slot 450that extends along a majority of the length of the inner sleeve 440.

The linear actuator assembly 400 further includes a screw 452. The screw452 is disposed in the second chamber of the inner sleeve 440. The screw452 has a first end 454 and a second end 456. The screw 452 also has anexterior surface 458. The exterior surface 458 of the screw 452 isthreaded. The first end 454 of the screw 452 abuts the bearing 420.

The inner sleeve 440 is disposed in the working chamber of the outersleeve 428. The screw 452 is disposed in the second chamber of the innersleeve 440. The threads on the threaded exterior surface 458 of thescrew 452 are disposed in and abut the threaded portion 445 of thecollar 443 of the inner sleeve 440. Stated differently, the threads ofthe exterior surface 458 of the screw 452 are threadingly engaged withthe threads of threaded surface 445 of the inner sleeve 440. The screw452 is attached to and abuts the bearing 420. The bearing 420 isdisposed around and attached to the second end 418 of the output shaft414.

When powered, the output shaft 414 of the motor 412 will rotate thebearing 420 and screw 452. The threads of the threaded exterior surface458 of the screw 452 will rotate within the threaded surface 445 of theinwardly projecting collar 443 of the inner sleeve 440. The inner sleeve440 will move axially along the screw 452. Referring specifically toFIG. 7, in order to prevent the inner sleeve 440 from rotating andextending past the screw 452, the slot 450 of the inner sleeve 440 isaligned with the aperture 436 of the outer sleeve 428. The pin 438 isinserted into the aperture 436 and the slot 450. The pin 438 will remainstationary as the slot 450 of the inner sleeve 440 moves. The innersleeve 440 can only be displaced the length of the slot 450 as the pin438 will stop the inner sleeve 440 at each end 451, 453 of the slot 450.Stated differently, the pin 438 and slot 450 define a stop mechanismthat limits the range of movement of the inner sleeve 440 axially alonga longitudinal axis relative to the outer sleeve 428 between a fullyextended position, as shown in FIG. 8, and a fully retracted position asshown in FIGS. 7 and 9.

The linear actuator assembly 400 includes a shaft 460 with the shaft 460having an axis. The shaft 460 also has an exterior surface 462 and abottom end 464. The linear actuator assembly 400 also has a gear 466with the gear 466 having an exterior surface 468. The shaft 460 isdisposed in and abuts the gear 466. The gear 466 is disposed within andat least partially supported by the housing 413 and engages the screw452 through the second aperture 437 in the outer sleeve 428. Theexterior surface 468 of the gear 466 has teeth. The shaft 460 also has amagnet 470 which is attached to and abuts the bottom end 464 of theshaft 460. The magnet 470 has a north pole 472 and a south pole 474.

The teeth of the gear 466 are disposed in and threadingly engaged withthe threaded exterior surface 458 of the screw 452. The gear 466 willrotate when the screw 452 rotates to change the linear position of theinner sleeve 440. The gear 466 rotates the shaft 460 and the magnet 470.As discussed above, as the magnet 470 rotates, the circular movement ofthe North Pole 472 and the South Pole 474 create a change in themagnetic field. The Hall Effect sensor 426 positioned below the magnet470 will detect the change in the magnetic field. The different magneticfield measurements detected by the Hall Effect sensor 426 areelectronically transmitted to the printed circuit board (not shown),which includes a central processing unit that can determine the linearposition of the inner sleeve 440 relative to the outer sleeve 428.Alternatively, the Hall Effect sensor 426 may itself have the capabilityfor determining the linear position of the inner sleeve 440 relative tothe outer sleeve 428 in the assembly 400. The gear 466 preferably has agear ratio with the screw 452 that would rotate the magnet 470approximately 300 degrees for the entire linear displacement of theinner sleeve 440. The large amount of rotation will provide goodvariation in the magnetic field between the different positions of theinner sleeve 440.

Similar to the linear actuator assembly 30, a first terminal 186 may bemounted to the linear actuator assembly 400. More specifically, aterminal end fitting 188 of the first terminal 186 is disposed within aninner region 475 of the inner sleeve 440.

Similar to the first embodiment shown in FIGS. 1-6, the first terminal186 may be designed to be mounted about a pin 220 of a gear shifterlever 224 and operate in a similar manner.

The present inventions have been described herein in an illustrativemanner, and it is to be understood that the terminology which has beenused is intended to be in the nature of words of description rather thanof limitation. Many modifications and variations of the presentinventions are possible in light of the above teachings. The inventionsmay be practiced otherwise than as specifically described within thescope of the appended claims.

What is claimed is:
 1. A linear actuator assembly comprising: a housing;a motor at least partially supported by said housing; an outer sleevecoupled to said housing and defining a working chamber with said outersleeve defining a longitudinal axis; an inner sleeve disposed withinsaid working chamber and moveable between a retracted position and anextended position along said longitudinal axis relative to said outersleeve with said inner sleeve having a first end and an opposing secondend and a series of threads disposed along at least a portion of saidinner sleeve; a screw coupled to said motor and extending outwardly fromsaid motor along said longitudinal axis with said screw having athreaded exterior surface engaging said threads of said inner sleevewherein rotation of said motor rotates said screw through said threadsof said inner sleeve and facilitates said movement of said inner sleevebetween said retracted and extended positions along said longitudinalaxis; and a stop mechanism limiting the movement of the inner sleeverelative to the outer sleeve in the extended position, said stopmechanism having a first portion associated with said outer sleeve and asecond portion associated with said inner sleeve with said first andsecond portions abutting each other when said inner sleeve is in theextended position to define a hard stop; wherein said first portion ofsaid stop mechanism is further defined as a cap mounted to an end ofsaid outer sleeve and wherein said second portion of said stop mechanismis further defined as a plurality of spaced apart tabs extendingoutwardly from an exterior surface of said inner sleeve with saidplurality of spaced apart tabs abutting said cap when said inner sleeveis in said extended position; and wherein said outer sleeve has aninterior surface defined by a series of inwardly projecting flanges withsaid flanges being spaced apart to define a plurality of guide slots,with one of said tabs being disposed within each of said guide slots andsaid exterior surface of said inner sleeve between said tabs beingdisposed adjacent to said interior surface of said outer sleeve betweensaid plurality of guide slots as said inner sleeve moves axially betweensaid retracted and extended positions.
 2. The linear actuator assemblyas set forth in claim 1 wherein said screw is coupled to said housingand remains longitudinally fixed relative to said outer sleeve and saidaxis during said rotation of said screw.
 3. The linear actuator assemblyas set forth in claim 1 wherein said outer sleeve is fixed to saidhousing and remains longitudinally fixed relative to said housing duringsaid movement of said inner sleeve.
 4. The linear actuator assembly asset forth in claim 1 further including a planetary gear assemblydisposed between said motor and said screw.
 5. The linear actuatorassembly as set forth in claim 1 further including a terminal endfitting mounted to said second end of said inner sleeve for movementwith said inner sleeve as a unit between said retracted and extendedpositions.
 6. The linear actuator assembly as set forth in claim 1wherein said cap includes a shoulder with each of said plurality of tabsdefining a shoulder with each of said shoulders of said tabs abuttingsaid shoulder of said cap when said inner sleeve is in said extendedposition.
 7. The linear actuator assembly as set forth in claim 1wherein said inner sleeve includes a nut having a threaded interiorsurface defining said series of threads.
 8. The linear actuator assemblyas set forth in claim 7 wherein said inner sleeve includes a slot andwherein said nut is fixedly disposed within said slot such that saidinner sleeve and said nut move as a unit during said movement of saidinner sleeve between said retracted and extended positions.
 9. Thelinear actuator assembly as set forth in claim 1 further including aprotective shield coupled to said second end of said inner sleeve suchthat said shield and said inner sleeve move as a unit during saidmovement of said inner sleeve between said retracted and extendedpositions with said protective shield extending over an exterior surfaceof said outer sleeve during said movement of said inner sleeve betweensaid retracted and extended positions.
 10. The linear actuator assemblyas set forth in claim 6 further comprising an adaptor coupled withinsaid housing, wherein said plurality of tabs abut said adaptor when saidinner sleeve is in said retracted position.
 11. The linear actuatorassembly as set forth in claim 10 wherein a section of said inner sleeveadjacent said first end of said inner sleeve is removed to define a gapin said inner sleeve such that said screw remains exposed and a gearremains engaged with said screw when said inner sleeve is in saidretracted position.
 12. The linear actuator assembly as set forth inclaim 1 wherein said outer sleeve is mounted to and extends from saidhousing.
 13. The linear actuator assembly as set forth in claim 1wherein said inner sleeve has an inwardly projecting collar with athreaded surface defining said series of threads.
 14. The linearactuator assembly as set forth in claim 13 wherein said collar isintegrally formed with said inner sleeve.
 15. A linear actuator assemblyas set forth in claim 1 further including a bracket assembly comprising:a mount having a first arm and a second arm; and an actuator bracketrotationally mounted to said first arm and said second arm about a firstpivot axis with said first pivot axis being transverse to saidlongitudinal axis and said housing being supported by said actuatorbracket to permit said housing to rotate about said first pivot axis;said actuator bracket having a bearing defining a second pivot axistransverse to said longitudinal axis and said first pivot axis, and saidhousing having a journal rotatably mounted about said bearing to permitsaid housing to rotate about said second pivot axis.